1. Field of the Invention
The invention relates to print control of an information processing apparatus for outputting print data based on application data to a printing apparatus.
2. Description of the Related Art
Hitherto, in copying apparatuses, a printing apparatus (hereinafter, also referred to as a printer) which can perform duplex printing by a two-sheet stay alternating feed has been proposed.
In such a copying apparatus, in the case of executing the duplex printing, it is necessary to execute what is called “sheet re-feed” in which after the first side was printed, a front edge and a rear edge of a sheet are reversed, and thereafter, the sheet is conveyed to a photosensitive drum until the printing of the second side is started. Since the printing cannot be executed for a period of time of such “sheet re-feed” in the duplex printing of a one-sheet stay, a print speed decreases.
As disclosed in Japanese Patent Application Laid-Open No. H06-015895 and Japanese Patent Application Laid-Open No. H10-003215, in the duplex printing by the two-sheet stay alternating feed, to solve such a problem, another sheet is printed by using the period of time during which the foregoing reversal and sheet re-feed are being executed, thereby preventing the decrease in the print speed.
To realize the duplex printing of the two-sheet stay alternating feed, in the copying apparatus, generally, by holding print data of a plurality of pages into a page memory of a large capacity, the print order is changed (in the normal printing, the printing is executed in order of pages such as 1, 2, 3, 4, 5, . . . ; however, in the case of the two-sheet stay alternating feed, the printing is executed in order of pages such as 2, 4, 1, 6, 3, 8, 5, 10, . . . ) or an error recovery is made by using the held print data in the case where an error occurred.
However, to execute the duplex printing by such a method, the memory of the capacity which can hold the print data of a plurality of pages has to be provided for the copying apparatus; unless otherwise, the error recovery cannot be made. To print at the highest print speed of a printer engine, a memory of a capacity which can hold the print data of four to eight pages is usually necessary.
A case where a “no-sheet error” occurred during the duplex printing by the two-sheet stay alternating feed will now be considered.
As also mentioned above, in the case of ejecting the sheets to a face-down tray in the duplex printing by the two-sheet stay alternating feed, the printing is executed in the following page order.
1B(2)→2B(4)→1A(1)→3B(6)→2A(3)→4B(8)→3A(5)→5B(10)→4A(7) . . .
where A indicates obverse side, B indicates reverse side, and ( ) indicates the number of pages.
Similarly, in the case of ejecting the sheets to a face-up tray, the printing is executed in the following page order.
1A(1)→2A(3)→1B(2)→3A(5)→2B(4)→4A(7)→3B(6)→5A(9)→4B(8) . . .
However, since there is such a difference that the order of the obverse and reverse sides of each sheet is merely exchanged between the case of ejecting the sheets to the face-down tray and the case of ejecting the sheets to the face-up tray, explanation will be made hereinbelow with respect to the case of ejecting the sheet to the face-down tray.
It is now assumed that three sheets have been set to a sheet feeding port. When the printing is executed, the printing can be executed up to 2A(3). However, since only three sheets have been set, the subsequent printing cannot be executed because the printing of 4B(8) uses the fourth sheet.
However, as for the third sheet, 3B(6) is printed and the sheet remains in the printing apparatus (in a duplex unit). If the apparatus waits until another sheet is set to the sheet feeding port in such a state, the sheets in the printer are dried and curled by the heat in the apparatus.
In the conventional copying apparatus, a technique in which 3A(5) is preferentially printed, thereby preventing the sheet from staying in the printer is also presumed in consideration of the above problem.
However, the conventional copying apparatus or the like as mentioned above has such a problem that since the memory of the large capacity is necessary to hold the print data, the costs rise.
Particularly, in a low-priced host-based print system, since bit map data is held as print data in the printer, a memory of a larger capacity is necessary and an increase in costs of the printer is further conspicuous.